The present application relates to semiconductors, and more specifically, to techniques for forming semiconductor structures. Semiconductor structures include complementary metal-oxide-semiconductor (CMOS) structures. CMOS technology may be used for constructing integrated circuits, and finds uses in microprocessors, microcontrollers, static random-access memory (RAM) and other digital logic circuits. CMOS structures may use complementary and symmetrical pairs of p-type and n-type metal-oxide-semiconductor field effect transistors (MOSFETs) for logic functions.
As demands to reduce the size of transistor devices continue, new designs and fabrication techniques to achieve reduced device footprints are needed. Vertical-type transistors, such as vertical field-effect transistors (vertical FETs or VFETs) are an example of such a new design. When forming vertical FETs, spacers are provided between and around vertical structures.